Light signaling means



Oct. 18, 1949. B. G. LAKE LIGHT SIGNALING MEANS Filed June '27, 1938 'la I INVENTOR. Buffon G. La7/ 5 VBY Patented Oct. 18, 1949 UNITED STATES OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 1 Claim.

My invention relates to. a light signalling means wherein there is light radiation outside the visible spectrum, and particularly to infra-red radiation so that the light is invisible, and the objects of my invention are:

First, to provide novel means producing powerful and short flashes of radiant energy in the infra-red spectrum;

Second, to provide a means of this class by the use of which extremely powerful and short flashes of light are produced and transmitted at the will of the operator;

Third, to provide a means of this class in which a light absorbing filter is used for rendering invisible the light that is used; and

Fourth, to provide a means of this class which is very simpleM and economical of construction, easy to operate, very emcient in its action and which will not readily deteriorate or get out of arder.

With these and other objects in view as will appear hereinafter, my invention -consists of the certain novel features of construction, combination and arrangement of parte and portions as will be hereinafter described in detail and particularly set forth in the appended claim, reference being had to ther accompanying drawings and to the characters of reference thereon which form apart of this application in which:

Figure l. is a perspective view of a casing showing my cylindrical parabolic reiiecter with the gas discharge tube positioned therein ready for use; Fig. 2 isa diagrammatic. view of my complete transmitter including thev operating parts andA portions and their connecting electric circuits; and Fig. 3 is a longitudinal sectional view of the gas discharge tube;

Similar characters of reference refer to similar parts in the views of the drawings:

The gas discharge tube I, external electrode 2, condenser 3, resistance ,transormer 5, rectier tube 6, resistance 'I, 4condenser 8; spark coil 9, contactor Ill, motor II, cylindrical parabolic reflector I 2 and filter nlm I3 constitute the principal parts of my light signalling means.

The gas discharge tube I preferably contains argon and this tube is positioned in its proper relation in the cylindrical parabolic reiiector I2 as shown in the drawings. Connected at its one end is the terminal of electric wire Ia and at its other end is the terminal of the electric wire I b. These terminals are in the form of internally connected electrodes of usual form. A Mounted on the middle of this gas discharge tube I is an external electrode 2 which connects with an electric wire 2a. Connecting the electric Wires Ia and Ib is an electric wire 3a, in which is positioned a condenser 3. This wire 3a terminates with a ground 3b. Positioned in the wire Ia is a resistance Il and connected with the wire Ib is a transformer 5 and electrically connected with the transformer 5 is a rectier tube 6. The electric wire 2a from the external electrode 2 connects with the high voltage terminal of a spark coil 9. This spark coil 9 is operated by means of a contacter I which discharges a condenser 8 through the primary of the spark coil 9. The condenser 3 is charged from the same voltage source as the main condenser 3, but through a higher resistance 'I of about one-half megohm. This contacter I6 is operated by the motor II. Connected across the wires 4a. and 6a is an electric wire tb. The spark coil 9 connects with the ground 9a by means of a wire 9b. Connecting with this wire 9b is the wire 8a in which the condenser 8 is mounted and the resistance 1. Fromthis wire ila, extends a wire Illa which connects with one side of the contacter I0. The other side of the contacter connects with the spark coil 9.

It will be here noted that the light produced by the electric discharge through the tube I is rendered invisible to the eye by means of a light absorbing filter which absorbs the visible light and transmits the desired invisible radiation. The glass wall of the discharge tube I, when composed of filter glass of suitable characteristics, may comprise the ilter; or the tube I may be made of clear glass and the filter applied to the outer surface of the tube as an adherent film on the outer surface or closely related thereto. It will also be noted that the argon gas used in the gas discharge tube I has a powerful spectrum in the infra-red region to which the photo-electric cells of the caesium silver oxide type are most sensitive. It will also be noted that the powerful lines in the red and infra-red spectrum of argon gas exists at 6965, 7067, 7503, 8115, 8425, and 9123 angstrorns. The visible light in the argon spectrum is removed by the absorption iilter of the tube I, the iilter being applied as hereinbefore described. It will also be noted that the argon gas discharge tube I generates very little energy in the infra-red spectrum which is outside the responsive range of the photo-electric cell, this being one of its greatest advantages over the incandescent lament or electric arc in both of which a large percentage of the infra-red energy is generated at wave lengths which do not effect the photofollows:

The gas discharge tube I is positioned at the focus of the cylindrical parabolic reflector l2 with a focal length of substantially one and onehalf inches. The aperture of the reflector is substantially twenty inches and the cylindrical axis about twenty inches. Connected across the tube terminals ia and ib is a high voltage condenser 3 with a capacity of about four microfarads. The condenser is charged through a 2000 ohm resistance c from a 1000 volt pulsating direct current source consisting of the transformer 5 and rectifier tube 0 which obtains its power from the 110 volt 60 cycle line 5a. The gas pressure in the discharge tube l is made such that the breakdown voltage of the tube is considerably more than 1000 volts. Therefore the condenser charges to the peak voltage supplied by the rectier'tube E and does not discharge through the tube until the path through the discharge tube l is ionized by a high voltage applied by the spark coil 9. This high voltage is applied to the external electrode 2 at the middle of the tube l through the wire 2a, it being noted that no internal connection is required to introduce the ionizing voltage. The spark coil 9 is operated by means of the contact maker i0 which discharges a one-quarter microfarad condenser 3 at 1000 Volts through the primary of the coil 9. This condenser is charged from the same voltage source as themain condenser 3 but through a higher resistance 1 about one-half megohm. The contactor l is driven by the driving motor l l. The speed of the signalling is limited only by the amount of energy that may be dissipated by the negative electrode of the gas discharge tube l without overheating. It is therefore desirable to use a large negative electrode for this reason.

Though I have shown and described a particular construction, combination and arrangement of parts and portions, and have described certain obvious modiiications, I do not Wish to be limited to this particular construction, combination and arrangement, but desire to include in the scope of my invention the construction, combination and arrangement substantially as set forth in the appended claims.

The invention herein described andv claimed may be used and manufactured by or for the Government of the United States of America for governmental purposes without the payment of any rolayties thereon or therefor.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A communication system employing directed beam invisible electromagnetic radiation; comprising a, directable parabolic reflector having a focal region, a gaseous discharge source of said radiation positioned in said focal region for emitting a narrow beam radiation pattern and having a. cathode and anode at the respective ends thereof, energy storage means externally connected between said cathode and anode of said radiation source, means continuously supplying direct current energy to said storage means at a potential below the discharge potential for the radiation source, an electrode external to said radiation source and disposed adjacent thereto adapted for initiating discharges therein, a circuit including a switch controllable at will by an operator for encodin'ga message in said beam, said circuit being connected from said direct current energy supply to ground, electrical coupling means in said circuit connected to said electrode and adapted for applying substantially said direct current potential to the electrode when said switch is closed, and energy storage means parallel connected across said circuit for instantaneously increasing the current iow to the electrode and for preventing sufficient re-energization of said electrode to cause further initiation of said discharge for an interval, whereby multiple initiations of radiation from a singleclosure of the switch are prevented.

BURTON G. LAKE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,345,586 Coblentz July 6, 1920 1,517,332 Wood Dec. 2, 1924 1,654,951 Toulon Jan. 3, 1928 1,933,856 Johas 1 Nov. 7, 1933 1,954,204 Hayes Apr. 10, 1934 2,073,247 Miller Mar. 9, 1937 2,116,689 Rompe 1 May 10, 1938 2,131,328 MichelsSen Sept. 27, 1933 '2,201,166 Germeshausen May 21, 1940 2,275,745 Eastman Mar. 10, 1942 FOREIGN PATENTS Number Country Date 24,724 France June 13, 1922 (1st addition to 526,282)

452,337 Great Britain Aug. 20, 1936 

